38 Our British Snails 



shape. Small. Brown. Common under rotten 

 branches and moss in woods. Hardly hibernates. 



Zoniioides nitidus — Chocolate-brown, with no 

 white round the umbilicus (as has H. nitudula). 

 Larger than, but not unlike, H. radiatula. Gre- 

 garious. Chiefly found by water ; also in damp 

 hothouses. Amphibious. 



Zonitoides excavatus. — Its broad and deep 

 umbilicus is quite distinctive. Mainly British. 

 Dislikes lime, and is most plentiful on the coal 

 measures. 



We come now to the Helicidse family and its 

 genus Helix, in which there are various sub-genera 

 of which the name is given in brackets. The 

 shell in this genus can wholly contain the body ; 

 the tentacles are always four ; the shell conical, 

 and rarely with a depressed spire. The word 

 " helix " is Greek, and means a coil. 



Helix {Gonyodiscus) rotundata. — Very common 

 under stones, moss, etc. Circular, flat, with a 

 large open umbilicus. Horn colour with brown 

 markings. 



H. (Pyramidula) rupestris, i.e. inhabiting rocks. 

 — Small. Gregarious. Dark brown. Mainly on 

 exposed dry walls and cliffs. 



H. [Punctum) pygmceum. — Very small. Yel- 

 lowish brown and glossy shell. Mainly on moist 

 dead leaves. Not unlike H. rupestris except as 

 to habitat. 



H. {Acanthimda) lamellata. — Small. Horn- 



